If you don't actively stay up with the tech, your understanding will atrophy. Consequently, because you intend to remain a PM, your tech will never be as strong as someone who is dedicated to it and you need to be okay with that.
Another classic example for this are engineering managers: people management (like project/product management) is its own discipline with a deep set of skills, research, training, etc. To become a good EM means you _will_ sacrifice some of your technical edge. That "deep technical understanding" that good EM's maintain is built on a foundation of years as a practitioner and, even then, requires continual investment.
I don't mean to discourage you, I just want to ensure you have realistic expectations.
Given all that and given your goals, I think you should just ask yourself a question only you can answer: how do you best learn?
If that's in the classroom, then go get that masters (online or in person). If that's with hands on projects, then set aside time for tinkering and get going. Likewise with books, videos, meet-ups, etc. You know what motivates you and what techniques keep you focused (because you'll need that discipline).
Regardless, I wish you luck and enjoy the journey!